Such antennas can be used in many different ways, especially for mobile radios. The transmitting and/or receiving stations are designed as mobile units and may be installed, e.g., on or in an automobile. A rod antenna is particularly well suited for such applications.
It is often desirable to transmit and/or receive in a plurality of wavelength ranges. In general, different antennas, which are mounted on a separate mast, are required for this purpose. Especially in mobile radio, such arrangements are disadvantageously uneconomical, susceptible to malfunction, and require much time for maintenance. It is often necessary to operate essentially simultaneously in two greatly different wavelength ranges, e.g., the meter range and the millimeter range. The longer wavelength, here the meter range, is needed for communication over greater distances, while the shorter wavelength is used for communication over shorter distances only. The millimeter range is particularly well suited for the latter, because it has quasioptical propagation properties. The abbreviation mm waves will also be used for millimeter waves below.